As materials applied to a tube system in a vehicle engine room, there are for example polyamide, polyester, and polyethylene resins, and polyolefin resins such as such as polypropylene resins and the like.
Since the materials are exposed to high-temperate environments for a long time, superior flame retardancy and long-term thermal resistance are essentially required. Materials to which a halogen-based flame retardant system including and/or satisfying the both properties is applied are used. However, due to recently intensified environmental regulation, requirements for eco-friendly materials and products are greatly increased and, thus, a research into the materials is actively underway.
As eco-friendly flame retardant systems which may be applied to polyolefin resins, metal hydroxides, phosphate-based materials, and the like may be considered. However, in the case of metal hydroxides, a large amount, namely, 40% or more, of flame retardant must be added and molding properties, water resistance, and mechanical performance may be deteriorated. Accordingly, phosphate based retardants are mainly considered (related prior literature: Korean Application Pub. No. 2013-0048426).
For example, since phosphate based retardants are added in an amount of 20% or more, properties thereof may be realized without use of halogens, heavy metals, and the like. However, due to an excessive addition amount of a flame retardant in the phosphate based retardants when compared with conventional halogen-based materials, it is difficult to effectively disperse the flame retardant and, thus, there are limitations in flame retardancy and extrusion properties. Therefore, there is an urgent need for development of a polyolefin-based flame retardant resin composition which may resolve these problems.